The invention relates to a system and method for solving manufacturing-scheduling (MS) problems. More specifically, the invention relates to a robust system and method for scheduling and planning manufacturing facilities and equipment based on pre-defined rules and goals.
Scheduling of manufacturing resources, for example, materials, machinery, man hours, and the like, in response to customer orders has been a significant concern and problem in the field of manufacturing for almost as long as products have been manufactured. The best use of manufacturing facilities and equipment results in greater productivity and profit. The vast majority of MS problems have been resolved by humans without the aid of computer tools, particularly in businesses where the maximum use of the manufacturing equipment and facilities has not been essential to the success of the business.
The increasing size of businesses in general, the increased competition and the need to provide improved customer service and customization have magnified the difficulties of MS problems to the point where efficient human resolution of the issues posed has become impossible or at best highly inefficient. Consequently, MS software tools and process have been developed to address these issues.
Existing MS software tools and processes can be extremely complex to use and understand, and, in general, do not adapt conveniently to a variety of different businesses in an efficient way to address all of the specific issues particular to each individual business. Further, many of these existing tools lack the capability of recognizing and adapting to the specific needs of individual businesses. This is, in part, because of the complex nature of trying to solve MS problems. From a generic standpoint, the complexity of the MS problem results in the interaction of a relatively large number of factors necessary to create an adequate solution to the MS problem. The complexity of the MS software development process to accommodate the magnitude of issues involved, and the complexity of MS modeling of the business which is emulated by the software, have not permitted previous MS software processes to be as successful as expected. As a consequence, many prior MS software application have required the business characteristics to fit a relatively fixed model, rather than allow the individual business characteristics to form the model. The complexity of an MS program is considerable, typically requiring tens or hundreds of thousands of lines of software code. Writing an extensive amount of software code creates opportunities for numerous errors, thereby requiring extensive trial and error use to eliminate the unforeseen errors, which may only be revealed from such use. Therefore, writing additional code is not a desirable approach to solving individual MS problems.
This complexity exists despite the fact that many of the basic concepts involved in the MS model itself seem almost intuitive. Concepts, which may appear intuitive in MS situations, are usually accomplished in MS software only with considerable difficulty, effort and creativity.
For example, many businesses have multiple concurrent goals at any given time. The goals of a business will often be conflicting. To illustrate, many companies proscribe to or at least attempt to proscribe to the concept of just-in-time. Businesses that follow the just-in-time concept typically manufacture and deliver products just-in-time to meet the customer""s due date. This allows manufacturers to minimize inventory reducing manufacturing and storage costs. However, many of these manufacturers may also like to maximize the use of their equipment or resources. That is, manufacturers prefer to minimize the idle time of their equipment or resources. Unfortunately, trying to merge these two goals will typically make the MS problem even more complex. In fact, sometimes these two goals may actually conflict with each other. Attempting to resolve conflicting goals of a business often produces mixed results.
Creating functional MS models has always been somewhat difficult and tedious. An MS model typically attempts to define and map the various resources available in a manufacturing facility. Unfortunately models for previous MS processes did not accurately represent the unique characteristic of resources. For example, the original MS processes were referred to as materials requirement planning (MRP). MRP is generally regarded as inadequate to meet current problems, primarily because MRP focused solely on the procedures for manufacturing a product and the timing associated with completion of the product.
One of the problems of MRP was that it was not very good at taking into account the limitations of resources. For example, MRP assumed an infinite capacity for each of the resources (e.g., work stations, tolls or people) available for use in the machining, assembly and production of a product. This assumption is simply not realistic. In reality, real resources have finite restrictions on capacity, operational capability, operational environment, etc. Thus, MRP generally ignored the operational constraints that limited how one could execute the manufacturing process.
Many manufacturing goals are difficult to accommodate in MS processes. For example, manufacturers sometimes strongly prefer that certain groups of products be produced by the same resource or resources in a particular sequential order. This is because there may be certain cost, operational or time advantages in doing so. The sequencing of production activities for different products in such a manner is generally referred to as xe2x80x9cproduct wheels.xe2x80x9d
As described above, many of the MS systems currently available are at best ineffective because of the often complex nature of manufacturing facilities, the often conflicting goals concurrently sought by manufacturers, and the constraints typically associated with manufacturing resources. Further, because of the extremely tight timeline that many manufacturers face daily, a robust MS system and method capable of scheduling manufacturing processes in real time would be highly desirable. Further, such a system and method would be even more valuable if it can take into account, the conflicting manufacturing goals, the complex relations between resources, and the resource constraints typically associated with a manufacturing facility.
To resolve the problems cited above, the present invention provides, among other things, a system and methods for scheduling manufacturing resources. In general, the present invention provides for a system and methods that schedule manufacturing resources by defining available resources, generating production methods and routes, and selecting routes based on user-defined goals. Further, the present system may use production wheels, packing out and block scheduling methods to optimally schedule manufacturing resources.
In a preferred embodiment, manufacturing data such as customer and internal orders, resource data, production methods, resource calendars, user goals, product wheels, SKU data, and the like, is stored in a database or a plurality of databases. After receiving and storing orders, one of the orders is selected for scheduling. Each order has an objective associated with it that identifies, for example, the finish goods or work-in-process that is the goal of the order. An MS model is created and stored in the database by defining available resources. Resources available for use in manufacturing are defined by identifying the constraints associated with each of the resources. A production method is generated based on the objective associated with an order selected for scheduling and the constraints as defined by the MS model. The production method identifies the production steps needed to attain the objective. Based on the production method generated, one or more routes are generated. One of the generated routes is then selected for scheduling based on user defined scheduling and/or routing goals. At least five types of scheduling goals are possible: maximizing resource utilization, just-in-time, minimizing production cost, minimizing cycle time and balance resource utilization. At least three types of routing goals are possible: fast, best, and fast on time.
According to another embodiment, product wheels are created and employed to prevent undesirable transitions from occurring. A transition is the process that a resource or a plurality of resources must undergo between succeeding assignments. By employing product wheels, undesirable sequencing of assignments may be detected and/or avoided.
According to another embodiment of the present invention, excess work-in-process may be packed out. As a by-product of manufacturing processes, excess work-in-process may be generated. By monitoring for and identifying excess work-in-process, and identifying and scheduling stored orders that consumes the excess work-in-process, the excess work-in-process may be eliminated.
According to another embodiment, block scheduling may be employed to reserve one or more resources for a product family. Reserving a resource may be accomplished by creating block calendars that are associated with the resource. The block calendars are divided into time intervals and product families assigned to those periods to reserve the resource for the product families.
As will be readily appreciated by one of ordinary skill in the art, the present invention provides for a robust system and method for scheduling manufacturing resources. Additional features and advantages are set forth in the description that follows, and in part are apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention are realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.